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This study investigated the effect of application of non-thermal atmospheric plasma (NTAP) on the topography and composition of the dentin surface, as well as the microtensile bond strength (μTBS) of a universal adhesive to NTAP-treated dentin. Exposed flat dentin surfaces from human third molars were either treated with NTAP for 10 and 30 s or untreated (control). The dentin-surface topography and chemical composition were characterized by atomic force microscopy (n = 3) and Raman confocal spectroscopy (n = 5), respectively. The μTBS (n = 8) of Scotchbond Universal to dentin was determined after storage for 24 h and 1 yr, either by direct water exposure or under simulated pulpal pressure. In-situ zymography was used to evaluate the influence of NTAP on the dentin-enzymatic activity. Non-thermal atmospheric plasma produced no remarkable topographical or chemical alterations at the dentin surface; only the amount of phosphate decreased following 10 s of treatment with NTAP. After 1 yr of direct water exposure, the μTBS of NTAP-treated specimens did not differ statistically significantly from that of untreated controls, whereas simulated pulpal pressure-aging resulted in a significantly higher μTBS for NTAP-treated dentin. The dentin-enzymatic activity appeared to be treatment-dependent, but the untreated controls showed more intense fluorescence within the hybrid layer. Scotchbond Universal maintained its μTBS strength after 1 yr of direct water exposure and simulated pulpal pressure, although remarkable statistical differences between treatments were observed depending on the aging condition.

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Biochemical composition of the skin changes in each layer and, therefore, the skin spectral profile vary with the depth. In this work, in vivo Confocal Raman spectroscopy studies were performed at different skin regions and depth profile (from the surface down to 10 μm) of the stratum corneum, to verify the variability and reproducibility of the intra-and interindividual Raman data. The Raman spectra were collected from seven healthy female study participants using a confocal Raman system from Rivers Diagnostic, with 785 nm excitation line and a CCD detector. Measurements were performed in the volar forearm region, at three different points at different depth, with the step of 2 μm. For each depth point, three spectra were acquired. Data analysis included the descriptive statistics (mean, standard deviation and residual) and Pearson's correlation coefficient calculation. Our results show that inter-individual variability is higher than intraindividual variability, and variability inside the SC is higher than on the skin surface. In all these cases we obtained r values, higher than 0.94, which correspond to high correlation between Raman spectra. It reinforces the possibility of the data reproducibility and direct comparison of in vivo results obtained with different study participants of the same age group and phototype.

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